This is not bad game design. I'm tired of people saying it is just because Destiny and Diablo let you change your loadout on the fly.
The UI to do these things is 100% bad design. UI is atrocious.
And people keep saying this game is more akin to Diablo than Destiny when the comparison was brought up. Fans and the developers themselves keep namedropping Diablo, so either specify exactly what they mean by that, or don't do it at all. The game is a loot game. It belongs to a genre, and while differentiation and innovation will be supported, just being different by itself doesn't immediately excuse some bad decisions. But really, people keep mentioning Diablo while propping up this game and probably should stop then, including devs. It's nothing like Diablo. The loot is not cosmetic, you can't equip on the fly, bosses apparently have no loot tables, it's not a set driven game, there is not as much variety and certainly there aren't unique modifiers to items to compare it. Loot rarity is gated by levels as well (according to GB) unlike Diablo where there are low level leendaries and set pieces.
So, OK, it's nothing like Diablo so people and developers should stop saying it. But it's also a rather poor, or content lacking example of a looter compared to the staples in the genre.